Excellent! That's a super product.
@ptrgrow has been good enough to post the PPFD map for the XS-1500 and the XS-1500 Pro is shown here. You can see that with the new light, the hot spot that the old light had in the center is gone. The older model had a higher PPFD right in the center but the values in the corners were much lower. Vipar changed the design and there's no more than 10% light loss across the canopy.
How to set up the light?
From
their FAQ page:
"Q: What height do I hang the Viparspectra Pro Series Grow Lights?
A: For seedlings, you should hang the lights 22 inches above the canopy. For the vegetative and flowering phase, you should hang the lights 12 inches above the canopy."
That's a very high hang height and you'd have to run at 100% to get good light on your plants so I'm not convinced that's the best approach.
They also advise that you turn the dimmer to 40% for the last two weeks of flower. I wouldn't recommend that.
OK, so what's the answer?
Check out the reply from
@ptrgrow up thread. I agree with the numbers for seedling but the numbers for veg and flower are very conservative. The simple answer is to give your plants as much light as they can tolerate. And, well, how much is that?
Hang height and Dimmer Percentage
Estimates
For seedling, 14" at 40% or 50% and see how the plant reacts. If it handles it well, bump it up a little but you're probably not going get much over 50% until your into veg. Once you've got some bulk in the plant, it's mature enough to go to 60% or so. If it starts tacoing, drop it by 10%. A few days later, try giving it a bit more. Once you hit mid-veg you should be at 80% and then 100% for flower.
PPFD Values
At the start of veg, at least 400, rising to 600 within a few weeks after the plant is established and then jump 100µmol every day. In veg, you'll get to 600 or 700 and then it will take a while to get to 800-1000. That range is where most cannabis grows will max out.
If your plant can't tolerate a given amount of light, it will let you know by the leaves "tacoing" ("canoeing") or rotating to a vertical orientation. When cannabis plants get too much light, they do that to reduce the amount of leaf area exposed to the light. They'll start turning in a few minutes and within about 30 minutes, it will be clear that your light setting is too high. I've had that happen twice and all I had to do was turn the dimmer down and the leaves rotated back. It doesn't harm the plant, assuming that you catch it quickly.
The above are estimates because I've always used a light meter and I use PPFD values but I think those are good numbers to work with. The most important think is to watch your plants and turn the dimmer up or down as appropriate.
A good sign is when your leaves "pray" because they elevate above horizontal, up toward the light. I believe that plants are right on the edge of too much light at that point but I have to admit that I haven't tested that theory. I've never seen any issues with plants that are praying ("they're so happy, they should get a room") but I have had a couple times when my plants have gotten too much light and it was easy to fix the issue - turn the dimmer down.
Why go through this? Because cannabis
is a light whore loves light and crop yield and quality increase in an almost linear manner as light levels increase. Plants that don't get much light won't yield much and they'll be tall and skinny with not a lot of branches and a small number of large leaves. A "well fed" plan (because plants get energy from the sugars they make because of light), will be bushy, with lots of leaves and short strong branches. That will turn into lots of flowers and it's much easier to harvest a shorter plant than a tall one.
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and is white fullspektrum light! you can use it ,for vegetative and bloom and can change it now if you want 40cm away 25-30% maybe!
